Extension

The QTViewer can be extended to display additional geometry (such as
buildings, GPS paths etc.) in a georeferenced ECEF context by deriving
a Renderer class from QTViewer’s Viewer class. In that class, we
overload the build_ecef_geometry() method, which constructs a scene
graph using libMini’s mininode class as a basis.

For example, we can add a cylinder as the north pole by specifying its
georeferenced position (mininode_coord), color (mininode_color) and
geometry (mininode_geometry_tube) and linking those node components
together as a simple scene graph. The so defined scene graph is
rendered on top of the earth and on top of any loaded libGrid or
VTBuilder tilesets: